Power plant for aircraft



Nov. 27, 1945. A H. R. FEDDEN Erm. 2,389,778

POWER PLANT FOR AIRCRAFT Filed Jan. 14, 1942 5 Sheets-Sheet 1 5Sheets-Sheet 2 Filed Jan. 14, 1942 A. H. R. FEDDEN El' AL POWER PLANTFOR AIRCRAFT Nov. 27, 1945.

Nov. 27, '1945. A, H, R FEDDEN ETAL 2,389,778

PowER PLANT FOR AIRCRAFT Filed Jan. 14, 1942 5 Sheets-Sheet 3 Nov. 27,1945. A, H, R FEDDEN ETAL 2,389,778

POWER PLANT FOR AIRCRAFT Filed Jan. 14, 1942 5 Sheets-Sheet 4 Nov. 27,1945. A. H. R. Fl-:DDEN ET Al.

POWER PLANT FOR AIRCRAFT 5 Sheets-Sheet 5 Filed Jan. 14, 1942 PatentedNov. 37, 1945 ino STATES PATENT ori-ics POWER PLANT FOR AIRCRAFTApplication January 14, 1942, Serial No. 426,778 lin Great BritainJanuary 17, 1941 1 Claim.

This invention relates to power plants for aircraft and has for itsobject to provide an iin proved construction and arrangement oftransmission gearing enabling two engines to be used to drive two ormore air-screws in various combinations. The two engines are arrangedwith their crankshaft axes parallel and preferably coaxial, and thedrive is transmitted from them to air-screws which are spaced awaylaterally from the engine axes.

Preferably two exactly similar engines are used set face-to-face so thattheir crankshafts rotate in opposite directions, thereby reducing to aminimum any torque-reaction or gyroscopic eiects.

According to this invention there is provided in a power plant for anaircraft, the combination with engines and airscrews arranged as aboveset forth, of means for engaging and disengaging either or both enginesfrom both airscrews.

According to another feature of this invention there is provided thecombination with the engines and gearing interconnecting them, of meansfor engaging and disengaging said gearing from either or both thelaterally extending shafts to the airscrews.

According to a further feature of this invention means is provided forautomatically disengaging the drive between the engines and theairscrews when the latter overrun the former. Preferably the said meansis interconnected with the throttle-lever and is maintained in thedriving position until the throttle-lever has been opened to apredetermined extent.

IThis invention permits the possibility of each engine being startedindependently, or run independently for test purposes. Moreover, it ispossible for one engine to be started from the other engine if thelatter is running, and when starting an engine it is possible to coupleit to an airscrew or airscrews so as to avoid any risk of the engineracing in cases where no other provision to meet this difliculty ismade. In the event of one engine failing during night it isautomatically disengaged from the airscrews and the other enginecontinues to drive both or all the airscrews. Furthermore, an economicalcruising speed can be obtained by disconnecting one engine and using theother engine to drive the airscrews at its most economical loading; insuch conditions it is possible to re-engage when necessary the enginewhich is not running. When the aircraft is gliding and no power is beingtransmitted by the engines to the airscrews, the latter tend to over-runthe engines and the drive between the engines and airscrews tendsautomatically to be disengaged. The driving connection is howevermaintained since, under these conditions the throttle is substantiallyclosed.

Finally since both engines are coupled to both or all the airscrews, itis desirable to be able to disconnect an airscrew should it fail or bedamaged in any manner, and this also is rendered possible by theconstruction according to the present invention.

In the accompanying drawings,

Figure 1 is a central sectional view showing the gearing connecting thetwo engines and its connection to the laterally-extending shafts whichdrive the airscrews.

Figure 2 is a sectional view of a detail on the line 2-2 of Figure l,

Figure 3 is a diagrammatic view showing the application of thisinvention to a large aircraft such as a iiying boat,

Figure 4 is a diagrammatic view of the power plant installation used onFigure 3, shown to a larger scale,

Figure 5 is a sectional view on the line 5-5 of Figure 4 and Figure 6 isa perspective view of a detail of the gearing shown in Figure l.

Referring rst to Figure 1, a portion of the casing of each of twoengines set face-to-face is indicated at I0, I I respectively with thecrankshafts I2, I3 extending therefrom towards one another. A bevel-gearI 4 is mounted independently of the crankshaft I2 on bearings I5 and itcan be coupled thereto by a friction-clutch I6 or positively engagedtherewith by a sleeve Il which is formed with internal axial splines toengage splines I8 on the crankshaft, and with external helical splinesI9 which engage internal helical splines on the bevel-gear. The sleeveI1 is capable of axial movement along the splines i8, and the helicalsplines I9 are so directed that the sleeve is self-engaging when theengine is running; the sleeve is thereby held in its engaging positionso long as the engine is driving the bevel-gear. When however theairscrews which are driven from/the bevel-gear I4 over-run the engine,the sleeve Il is automatically disengaged from the bevel-gear I4 by thehelical splines. The function of the friction-clutch I6 is to bringabout synchronism of speed between the engine and the bevel-gear priorto the engagement of the positive drive.

The friction-clutch I6 and positive-clutch l1 are both hydraulicallycontrolled by oil under pressure driven from an engine-driven pump andfor this purpose one set of the friction-plates of the clutch I iscarried by an annularrmember 2l surrounding the crankshaft and the otherset is carried by the bevel-gear I4. nular member 2l is formed on itsouter face with a dished recess 2| which receives an annularpiston-likemember 22 and the supply of oil under pressure is delivered through aduct 2l which opens into the member 22. 'I'he space 2I is bounded on itsinner periphery by flanges on the member 2l and piston-like member 22 asshown at 24,'and these flanges are of such axial length that when oilpressure is admitted to the chamber 2| to press the member 20 towardsthe left and engage the friction-clutch I6, the two flanges 24 separateand admit the pressure-oil to the space 25 from which it passes by theduct 26 to a space 21. Whenthe clutch-sleeve I1 is in its disengagingposition, its end 25 lies within the space 21 and constitutes apiston-like member therein so that the application of oil under pressureto it forces it towards the left until, at its left-hand end, thehelical splines I9 enter into engagement, and thereafter the sleeve isdrawn into full driving engagement with the bevel-gear. When the sleeveI1 is in its disengaged position it is retained therein by aspringpressed ball 29 which retains it except when oil pressureisapplied to move it.

The other crankshaft I3 is provided with a bevel-gear 30 and coupledthereto by mechanism exactly similar to that already described for theshaft I2 and gear I4, but in this case the positive driving sleeve 3l isshown in its disengaged position.

. 'I'he two bevel-gears I4 and 30 are exactly similar and they both meshat opposite ends of a 'diameter with bevel-pinions 32, 33 respectively2l to displace the member 20 which slides on the piston-like member 22and thereby brings the plates of the clutch I6 into frictionalengagement with one another. A drive is thereby imparted to thebevel-gear I4 (or 30 as the case may be) thereby synchronising the gearwith the crankshaft. Ihe movement of the member 20 The 3119? whencompleted disengages the flanges 24 and admits the pressure-oil to thespace 21 so as to initiate the movement of the clutch-sleeve I1 againstthe retaining action of the spring-pressed ball 29, to bring the helicalsplines I9 into engagement, and then, as stated above, the sleeve isdrawn into full driving engagement and the bevel-gear I4 is positivelycoupled to the shaft I2. The oil in the chamber 21 can escape throughradial holes therein after the end 28 of the sleeve l1 has moved a.suillcient distance to engage the splines I9, and finally can escapefreely from the end of the space 21. Upon release of the oilpressure,the friction-clutch I6 returns to its disengaged position.

With .this hydraulic clutch control, it is possible to-start an engineby its electric or other the oil pump and builds up the necessaryoilpressure to effect engagement of the clutch when desired, as abovedescribed. It is therefore not essential that the engine should berunning under its own power before the airscrews are en- 88861 As statedabove, the second engine is provided with exactly similar clutchingarrangement whereby it may be engaged with its bevel-gear 3l, but thehydraulic systems of the two engines are suitably interconnected so thatwhen one engine is running, its oil-pressure may be used 'to engage theclutch of the stationary engine;

assuming that the engine I0 is running and driving the bevel-gear I4 andbevel-pinion 32, the bevel-gear 30 is thereby driven and the admissionof oil-pressure to the clutch system of the engine I I engages itsfriction-clutch 34 which starts the engine II and nally positivelyengages it with its bevel-gear 30. Alternatively, of course the engineII may be started by means of its own electric or other starter if sodesired.

As was stated above, the positive engagement between an engine and itsbevel-gear is effected by means of the helical splines on the sleeve I1and these are so arranged that in the event of an airscrew over-runningan engine this clutch is automatically disconnected. This is necessaryif one of the engines fails during flight, but it is undesirable thatdisengagement should take place when the aircraft is gliding. that is tosay when the throttle is closed or substantially so. Accordingly, avalve is provided in the hydraulic system of each engine to control thesupply of oil through the conduit 23 and each valve is connected withthethrottle-lever of its associated engine in such a manner that thefriction-clutch is maintained in its driving position until the throttlehas been opened to a predetermined extent. The airscrews are thereforefree from the engine or engines when the throttles are closed orsubstantially so.

As so far described a drive can be transmitted from the engine to thebevel-pinions 32, 33 and these drive laterally-extending shafts whichtransmit the drive to the airscrews as will now be described withreference to Figure 2. 'Ihis drawing shows one of the bevel-pinions 32,at the top of the drawing, and at the bottom, the shaft which it drives.It is desirable that it should be possible to disconnect the shaft 35from the driving gear in the event of damage to an airscrew and a clutchmechanism is therefore provided between the bevel-pinion 33 and theshaft 35. The pinion 33 is formed integrally with a short shaft 42 whichis mounted on a ball-bearing and journal-bearing 4|. A sleeve 43 issplined at 44 on to the shaft 42 and carries a flange 45 formed withteeth 46 on its outwardly directed face, to engage cooperating teethformed on a flange 41 on a sleeve 48 mounted onthe journal-bearing 4I.The sleeve 48 is mounted in a suitable ball-bearing and has splinedengagement at 49 with a sleeve 58 which drives through internal teeth 59the shaft 35, this construction being used to provide a slightflexibility of the driving connection to the shaft.

The clutch-teeth 46 on the members 45, 41 above-mentioned arehydraulically controlled and for this purpose a dish-shaped memberencloses the toothed end of the shaft 45 and is secured by studs 5| tothe flange 45. The member 41 therefore acts like a piston in the member55 with a space 52 on one side and 53 on the other side.

A supply of high pressure-oil is provided by a conduit 54 (shown nearthe top of the drawing) asserts and the oil is directed to one or otherof the chambers d2, tti by means of a tubular valve member be, whichslides ina valve body ist (whereto the oil is supplied) and in a secondvalve body 5l. The chamber 52 communicates by radial ducts 5t, anannular groove 59 and a radial duct 6@ with a groove t! on the innerface oi the valve member 5l, and the Vchamber 53 similarly communicatesby a passage e2, groove 63, passage td, groove b5 and passage tt with asecond groove el] on the inner face of the valve member di. The tubularvalve member 55 is provided with radial ports t@ which cany be broughtinto register by longitudinal movement ci the member 55 with either ofthe annular recesses tl or El, and when in register with one of them itopens the other to the interior of the shaft t2 to allow the escape ofcil thereto. The upper,4 end of the valve tube 55 is provided with portsle which, in either position to which the valve 55 can be adjusted, opencommunication from the supply conduit d@ to the interior or the tube 55and thence to one or other of the chambers 52, e3. When oil is suppliedunder pressure to the chamber 52, the sleeve t3 and cylinder member 5dare moved upwards disengaging the clutch teeth d@ and therebydisengaging the drive to the shaft 3b. During this movement any oil inthe space b3 escapes through a groove into the passage @2 and thence asdescribed above to the interior of the shaft d2. When the control of thevalve tube 55 is released, it is returned by a spring 'ii at its upperend to its initial position thereby admitting oil to the chamber 53 andre-engaging the clutch-teeth iid,

The drive from the shaft 35 and the similar laterally-extending shaft onthe other` side of the engine axes is transmitted to the airscrews inany convenient manner depending upon the design of the aircraft. Thusthe gearing hereinbeforedescribed may be used for the power plant of anaircraft as described in the specification of concurrent British patentapplication No. 701/41, in which case the two engines are mounted withinthe fuselage with their crankshaft axes lying 1ongitudinally thereof.The laterally-extending shafts 3E are arranged within the wings of theaircraft and at their outer ends a drive is transmitted to airscre'wshafts lying parallel with the 1ongitudinal axis of the aircraft. Inthis case the connection between the shaft 35, and the airscrew shaft ispreferably of the kind described in the specication of concurrentBritish patent application No. '702/41. The transmission gearing,however. may also'be used with other arrangemen of aircraft asillustrated for example in 1 3 and 5.

In these drawings, Figure 3 illustrates diagrammatically the generallay-out of the aircraft comprising a fuselage l2 withlaterally-extending wings 13; twopairs of engines are mounted in themanner above described within each of the wings, as indicated in Figure4 and shown to a larger scale in Figure 4. The two engine-s of each pairare indicated respectively at 15, 16, and they are mounted with theiraxes normal -to the longitudinal axis of the aircraft with thetransmission gearing disposed between them. The laterallyextending shaft35 extends forward beyond the leading edge oi the wing to drivecounter-rotating airscrews ll. Alternatively,l a single airscrew can beused in this position or tractor 'airscrews can be used in front of thewing and a single pusher airscrew at the rear edge of the wing drivenfrom the second laterally-extending shaft, or there could be twocounter-rotating pusher airscrews at the trailing edge of the wing.

Each pair of engines is enclosed in. a sealed cabin 18, access to whichis provided through pressure doors so that the engines are accessiblefor attention during night. Air inlet duct/s 79 in the leading edge ofthe wing supply the air for lthe engine and cabin, and the cooling airis led in around the engine cylinders by means of a cylindrical cowl 8G,flowing longitudinally of the engine axis into lthe space between theengines and thence by an outlet duct BI to the trailing edge of thewing. The exhaust gases are carried out by tail pipes 82 situated in theduct 8i, and preferably the general arrangements for cooling the engineare as described in the specications of concurrent Tritlsh patentapplications Nos. 703/41, 704/41 and 705/41.

We claim:

In a power plant for aircraft, the combination with two engines eachhaving a power shaft and arranged with the power shafts in line with oneanother, a pair 'of driving bevel gears coaxial with the power shaftsand associated one with each power shaft, a pair of engine clutchesassociated one with each power shaft and arranged each to clutch itspower shaft to the associated driving bevel gear, a pair of coaxialdriven bevel gears each meshing with both driving bevel wheels, twocoaxial airscrew shafts, coaxial with and associated one with each of,the driven bevel. gears, and a pai; of airscrew clutches associated onewith each airscrew shaft and arranged each to clutch its airscrew shaftto the associated driven bevel gears.

HUBERT ROY FEDEN. FRANK MORGAN OWNER. FREDERICK tmTCALF THOMAS. STANIEYWALT@ MANSEIL.

